Physiology, Homeostasis

Homeostasis is a term that was first coined by physiologist Walter Cannon in 1926, clarifying the 'milieu intérieur' that fellow physiologist Claude Bernard had spoken of ­­in 1865. 'Homeo,' Latinized from the Greek word 'homio,' means 'similar to,' and when combined with the Greek word 'stasis,' meaning 'standing still' gives us the term that is a cornerstone of physiology. Carl Richter proposed that behavioral responses were also responsible for maintaining homeostasis in addition to the previously proposed internal control system, while James Hardy gave us the concept of a setpoint or desired physiological range of values that homeostasis accomplishes. The body's many functions, beginning at the cellular level, operate as to not deviate from a narrow range of internal balance, a state known as dynamic equilibrium, despite changes in the external environment. Those changes in the external environment alter the composition of the extracellular fluid surrounding the individual cells of the body, but a narrow range must be maintained to stave off the death of cells, tissues, and organs.